1. Field of the Invention
This invention relates to an apparatus for preparing frozen products such as ice-cream, soft ice cream and the like.
2. Description of the Prior Art
In general, one of the matters to be given the most consideration in designing an apparatus for preparing frozen products is the operational control of a freezing system used to bring about freezing temperature in a freezing chamber of the apparatus. This is important to finish liquid mix supplied to the freezing chamber to an ice-cream base having a proper hardness (viscosity).
As an example of an operational control device of a temperature detecting system which has been used widely, a control device is disclosed in the Japanese Utility Model Early Publication No. Sho 53(1978)-121199. In this control device, in view of the general composition of the refrigerating chamber (freezing chamber) where a taking out port is provided in the front and a material input is provided in the rear, the front thermostat which controls a compressor motor of a refrigerating system by detecting the temperature near the outlet of the refrigerating chamber and the rear thermostat which controls a compressor motor by detecting the temperature near the material inlet of the refrigerating chamber are provided in series and it is designed that the compressor motor is stopped by the front thermostat and that it is re-started by the rear thermostat.
It is mentioned that such a conventional device is effective for continuous sale because freezing operation can be re-started in quick response to the replenishment of materials. However, because of the above-mentioned quick response, the device is inherently disadvantageous in that ice cream near the taking out port in the front of the refrigerating chamber is frozen too much when sales are made intermittently.
In the conventional ice cream manufacturing machine, a product remaining in the freezing chamber is collected and stored in a refrigerator at the end of the sale day and the collected product is used again on the following sale day. On the other hand, as the used machine is not operated until the following day, the freezing chamber must be cleaned and sterilized under governmental sanitary laws.
For example, disclosed in the Japanese Patent Publication No. Sho 56(1981)-9093 is a soft cream manufacturing machine which requires collection of soft cream remaining in the refrigeration cylinder (freezing chamber) after the sale day is over and then cleaning of the refrigerating cylinder.
Such a machine is disadvantageous in that it required troublesome collecting and cleaning after sales every day, requiring a gret deal of labor.